Solution

Estoppel is a legal principle that prevents a person from denying or contradicting a statement that they previously made. This means that if a person makes a statement or representation of fact to another person, and that other person relies on that statement to their detriment, the first person may be prevented from denying or contradicting the statement if it would be unfair or unjust to allow them to do so. For example, if a person sells a car to another person and represents that the car has never been in an accident, but it later turns out that the car was in fact in an accident, the seller may be estopped from denying that the car was in an accident if the buyer relied on that representation to their detriment, such as by paying a higher price for the car than they would have otherwise. Waiver, on the other hand, is the voluntary and intentional relinquishment of a known right or claim. Denial refers to contradicting or refuting a statement or accusation.